The invention relates generally to the manufacture of rotor blades and more particularly to the manufacture of a wind turbine blade with a flat bottom air foil.
Wind turbine blade design is critical to the overall performance, reliability and cost of modern wind energy conversion systems. The wind driven rotor typically comprises two or three radially extending blades connected at the center by a rotor hub which in turn is drivingly connected to an electrical generator or alternator. Thirty foot diameter rotor designs are capable of generating six kilowatts of electrical energy at moderate wind speeds. Each fifteen foot blade comprises a complex elongated geometry of flat twisted and convex surfaces. While wood is an excellent choice for this type of rotor blade because of its physical properties and absence of electrical interference, shaping techniques used in the past have relied on a variety of complex blade carving machines of the tracer type designed to carve both the top and bottom side of the air foil. These machine require small cutter widths and multiple passes to accurately carve an air foil. Thus, the machinery is not only expensive but labor intensive to use in the manufacturing process. Nevertheless, the resulting blades vary widely in stiffness, weight and strength characteristics from piece to piece. This variability, which can adversely affect rotor performance, results in a lower yield thus increasing the cost of an already costly process.